1. Field of the Invention
The present invention relates to the field of optical sorting of desirable materials from mixtures that also contain undesirable materials.
2. Description of the Background Art
The harvesting and gathering of agricultural products into bulk accumulations on a commercial scale usually results in a certain percentage of undesirable materials intermixed with the desired agricultural product. The undesired material may include trash, debris, diseased product, and the like. Machines of varying effectiveness are known in the prior art for sorting the desired product from the undesirable material. In providing a sorting device, the goal is to eliminate as much of the undesirable material as possible with as little human labor and waste of desired product as possible.
The prior art contains a number of apparatus and processes for measuring constituents of samples, such as grains, for moisture, protein and oil content utilizing near-infrared radiation energy. For example, U.S. Pat. Nos. 4,466,076 and 4,627,008, both to Robert D. Rosenthal, the inventor of the present invention, disclose instruments that can measure constituents of a sample by transmitting near-infrared radiation energy through the sample. These instruments utilize a phenomenon that certain organic substances absorb energy in the near-infrared region of the spectrum. By measuring the amount of energy absorbed by the substances at specific wavelengths, precise quantitative measurements of the constituents of a produce can be determined. While such instruments have proven extremely useful for measuring one or more constituents of a particular sample, near-infrared light transmittance technology has not heretofore been suggested as suitable for separating desirable materials from mixtures that also contain undesirable materials.